Synthesis and in vitro biological activity of chalcone derivatives as potential antiparasitic agents

Kinetoplastids are a group of flagellated protozoans including medically important parasites of the genus Trypanosoma and Leishmania. The corresponding diseases have afflicted humans for centuries. In an effort to combat kinetoplastid infections, a set of 21 chalcones was synthesized and evaluated for their in vitro anti-protozoal efficacy against Trypanosoma brucei, Trypanosoma brucei rhodesiense, Trypanosoma cruzi, and Leishmania infantum. To ensure safety, these compounds underwent a selectivity evaluation by assessing toxicity against a human lung fibroblast cell line. Compound K4 exhibited remarkable and selective trypanocidal activity against T. b. brucei with IC₅₀ value of 0.31 ± 0.27 µM and T. b. rhodesiense with IC₅₀ value of 0.96 ± 0.86 µM. Compound K9 also showed significant trypanocidal activity against T. b. brucei (IC₅₀: 0.45 ± 0.14 µM) and T. b. rhodesiense (IC₅₀: 0.93 ± 0.51 µM). In both compounds, electron withdrawing groups are appended to the styrenyl moiety.